Machine for hobbing worm-gears



(No Model.) 3 Sheets-Sheet I,

V. W. MASON, Jr. MACHINE FOR- HOBBING WORM GEARS.

No. 537,214. Patented Apr. 9, 1895.

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V. W.v MASON, Jr. MACHINE FOR- HOBBING WORM GEARS.

N0. 587,214. Patented Apr. 9, 1895.,

I W I/ 25555 or roughing out with an ordinary cutting tated at a certainconstant speed, which may gear to be hobbed. Center spindles carry[UNITED STATES PATENT VOLNEY w. MASON, JR, or HYDE PARK, MASSACHUSETTS.I

MACHINE FOR HOBBING WORM-GEARS.

SPECIFICATION forming part of Letters Patent No. 537,214, dated April 9,1895. Application filed January 25, 1894- Serial No. 498,033; (Nomodel.)

To all whom it may concerm- Be it known that I, VOLNEY W. MASON, Jr., ofHyde Park, countyof Norfolk, State of Massachusetts, have invented anImprovement in Machines for Hobbing Worm-Gears, of which the followingdescription, in connection with the accompanying drawings, 'islaspecification, like letters and figures on the drawings representinglike parts.

Heretofore worm'gears have been hobbed by a continuously rotating hobengaging the teeth of thegear which is held loosely between the centerspindles, the gear being rotated or dragged round by the hob, as thelatter sinks radially into the work. 1 The 'constant dragging action ofthe hob against the teeth of the gear results iii forming or shaping theteeth incorrectly, more or less varying their pitch, and also rapidlywears away one side of the hob. Worm gears have also been cut insubstantially this Same way, the teeth being previously generated bycasting,

tool.

This invention has for its object to construct a machine especiallyadapted for hobbing or cutting worm gears, whereby the defects abovenoted may be overcome, andconsists essentially in so constructing andarranging the various parts of the machine that a continuously rotatinghob or cutting tool is made to gradually sink radially into a positivelyrotatedblank or worm gear, saidblank or gear rotating at a definiteratio with relation to the cutting tool, according to the number ofteeth to be cut or hobbed.

In carrying out this invention the shaft or arbor carrying the hob orcutting tool is robe varied as desired, and the worm gear'to be hobbedor blank to be cut to produce a worm gear is likewise rotated at acertain constant speed, the ratio of one to the other. varying accordingto the number of teeth to be cut in the blank, or the number of teeth inthe worm the worm gear or blank,one or both of which are rotated bysuitable gearing connected with and positively actuated by the meansemployed for rotating the hob-carrying shaft, as for instanceitmay beconnected with the insure the gear and cutting tool being rotated at acertain ratio, one with relation to the other. The spindle drivingmechanism or 'gearingis adjustable for the different speeds which it isdesired to rotate the gear or blank. In addition to the cutting tool anddriving spindle of theblank or worm gear, each positively rotating, theknee or support carrying said driving spindle is made vertically movable, that the cutting tool may sink radially into the blank or gear asit revolves, and mechanism is preferably-provided for so raising theknee which is connected with the driving mechanism of the other parts,in order that the knee may be raised automatically. The spindle drivingmechanism is such as to permit the knee to rise and fall verticallywithout disarranging its operative connection with the hob-carryingshaft, so that the relative ratios of speed may be continuouslymaintained. The head or frame carrying the driving spindleis Secured toa table which is adapted to be moved horizontally on a carriage which islikewise movable horizontally, but at right angles to the horizontalmove ment of the table, said carriage being supported by or upon thevertically moving knee. The spindle driving mechanism or gearing isadapted to be disconnected from the spindle or head carrying it, so thatsaid head may be utilized for other work than cutting or hobbing wormgears.

My device is herein represented as an attachment to an ordinary millingmachine, whereby other work of a general machine shop nature may bedone, when the bobbing or gear cutting attachment is disconnectedtherefrom.

,Figure 1 shows a left hand side elevation of a machine for hobbing orcutting worm gears, embodying this invention; Fig. 2, a front elevationon an enlarged scale of the head and adjoining parts of the machine;Fig. 3, a right hand side elevation of the head and adjoining partsshown in Fig. 2, and Figs. 4, 5, 6, 7 and 8,-details to be referred to.

The standard or column A mounted upon a base B and the arch C, are ofany usual or suitable construction to support the working parts, andtogether'with the knee K, which is adapted to slide vertically in asuitable guideway on the column A, are as usual in milling machines. Avertical feeding screw 7.: is provided for the knee K which has at ornear its lower end a worm'wheel which is engaged and driven by a worm ksee dotted lines Fig. 1, secured to a shaft passing through the columnA, and having upon its rear end a cone pulley 70 which is thrown intoand out of engagement with the shaft by a suitable clutch k On a standor bracket 7c, secured to and projecting rearwardly from the column A,is mounted an intermediate cone pulley 70", which is in alignment withbut above the cone pulley It. On the upper part of the frame work of themachine a shaft or arbor a has its bearings and has secured to its rearend a cone pulley a, in alignment with but above the cone pulley 75 Thecone pulleys a, 7s, 7c, are connected by belts 717 k, and by theiremployment the speed of the worm shaft 7.; may be varied. The shaft acarries a hob a or other cutting tool which may be of any usual orsuitable construction. A cone pulley a is mounted loosely on said shafta, which receives upon it the driving belt, and a pinion a also mountedloosely upon the shaft a, and made fast to and driven by said conepulley a which engages a toothed wheel a secured to a quill or sleeve a,mounted upon an eccentric shaft a turning in suitable hearings on theframe, a pinion a being also secured to said quill a thereby rotating inunison with the toothed wheel a. The pinion a engages the spindle gear afixed to the shaft a. By turning the eccentric shaft a the toothed wheela and pinion of are thrown into and out of operative engagement with thepinion a and gear a on the shaft a. This driving mechanism or gearing iscommon in milling machines, and is herein termed the back-gearingthereof, and in different forms of milling machines is slightlydifferently constructed, yet capable of accomplishing substantially thesame results. The hob or cutter-carrying shaft 0. is rotated by the saidback-gearing.

Upon the quill a on the eccentric shaft a a pinion b is secured whichengages a toothed gear b secu red to a short shaft b see dotted linesFigs. 3, 6, and 7, having its hearings in a box b placed in a slot 12formed longitudinally in an arm N, which is loosely mounted upon thequill a, and thereby movable on the axis of the back-gearing shaft a.The toothed gear b is the prime gear borne by the swinging arm b and isengaged and driven by the backgearing of the machine. The short shaft 6passes through the box 11 and has secured to its oppositely projectingend a toothed gear 12 which engages a pinion Z), secured to a shortshaft 12', see dotted lines Figs. 3, 6, and 7, contained in a box Z9likewise placed in the longitudinal slot N, in said arm The boxes Z2 19are or may be made substantially alike, each comprising a tubularbushing having flattened sides to be received within and movedvertically in the slot b and having at one end a flange b, and at theother end screw threads adapted to receive a binding nut Z2 providedwith spanner holes by means of which it may be turned to frictionallysecure the box at any desired part of the slot 11 By providingadjustable shafts b If, it will be seen that the intermediate gears Z2,I)", may be removed and others of different diameter substituted forpurposes to behereinafter explained, or such changeable gearing may bevaried to suit the work which is to be done.

A yoke c is secured to a sleeve 0' pinned or otherwise secured to theshaft 12 or said yoke may be secured directly to the hub of the pinionb", and a yoke 0 on the end of a tubular rod or shaft 0 is placedadjacent and at right angles to the yoke c, and a ball or intermediatepiece 0 is interposed between and connected with said yokes by suitablepins constituting a universal joint connection between the tubular rodor shaft 0 and the shaft 12 Contained within and projecting from theopposite end of said rod or shaft 0 is a spline rod or shaft 0 having atelescopic movement with relation to the tubular rod or shaft o and tothe end of said rod or shaft 0 a universal joint connection similar tothat just described is provided,connecting itwith a sleeve 0 pinned tothe end of a worm shaft 0 See dotted lines Fig. 3. Fixed to said wormshaft 0 is a toothed gear 0 and beside it, and in mesh with it, is atoothed gear c", see Fig. 4, mounted loosely upon a stud, said gear 0"having a hub upon which the sleeve 0 may be pinned when desired, so thatthe worm shaft 0 may be turned in one or the other direction accordingto whether the sleeve is pinned directly to the worm shaft or to the hubof the gear 0". The worm shaft 0 has its hearings in a bracket d,adjustably secured to one end of the framework, and bears a worm d,which engages the worm wheel d secured to a disk d which is fixed to acenter spindle d having its bearings in a head (1 which is dovetailedinto or otherwise secured to the table (1.

The blank n which may be a blank to be cut to form a worm gear, or aworm gear to be hobbed, is held between the center spindles d, and d,upon a suitable arbor, which is connected with the center spindle d bymeans of a suitable clutch or dog 6. The blank n is driven constantly bythe center spindle d worm wheel d worm d, telescopic shaft connectingsaid worm with the pinion L, and the intermediate gearing connected withthe back-gearing of the machine, while the hob or cutting tool is drivenconstantly by the shaft a, and the knee K is constantly raised by thefeeding screw 70. For worm wheels of different sizes the knee may beadjusted vertically, and for worm wheels having different numbers ofteeth the intermediate gearing on the swinging arm 11 will be changed asheretofore explained, so that the ICO proper ratio may be obtainedbetween the number of turns of the hob or cutting tool, and the numberof teeth in the wheel to be hobbed or out. As for example if the blankto be hobbed has fifty teeth, the blank will be turned exactly onerevolution while the hob is turned fifty revolutions.

- The wormwheel d is detachably connected with the plate or disk d sothat worm wheels having differentnumbers of teeth may be substituted ifa wider variation is required than can be obtained by the change ofintermediate gearing, and furthermore if desired different worm wheels(1 may be employed in lieu ofchanging the intermediate gearing.

It is obvious that the plate or disk d may be omitted and the worm wheel(1 secured directly to the spindle d, or said disk and worm wheel may beindependently secured to the spindle.

The bracket d is vertically adjustable upon a plate d secured to the'endof the head d by a binding bolt c1 and is provided with a suitable latchor limitingmstop m, see Fig. 8 and dotted lines Fig. '5, whichdetermines when it is adjusted so as'to accurately mesh with thewormwheel 01 and by pressing inward the latch and lowering said bracketthe worm d is thrown out of mesh with the worm wheel (1 in whichposition of the parts the apparatus may be used for other machine shoppurposes. For such general machine shop work I have provided a wormwheel (1 which is secured to the center spindled and for simplicity ofconstruction the said worm wheel 01 may be made integral with the disk(1 A worm d is secured upon aworm shaft (1 having its bearings in ayokeor frame d, and a crank is or may be secured to said worm shaft, bymeans of which it may be turned, said crank moving overa fixed dial dThe worm d engages and rotates the worm wheel (1 and upon the face ofsaid worm wheel d a suitable number of teeth or notches are providedwith which co-operate a suitable latch or detent (1 for retaining saidworm wheel in whatever fixed position it may be placed, so that eitherthe series of notches or the worm wheel indicating device may beemployed according to the work being done. The center spindle (1 may beturned manually by a spanner whichengages the spanner holes 2 in thedisk 61 In lieu of the center spindles d, d, carrying the blank to becut I may employ as an equivalent therefor, an arbor or any othersuitable rotating device.

In lieu of employing cone pulleys a, 7c,

and connecting belts, the shaft 70 may be connected with the shaft a bygearing or any other suitable connecting mechanism, but I prefer toemploy the belt mechanism shown because if for any reason the kneeshould be advancing or rising too fast as compared to the action of thecutter upon the work being done, said belts would slip before the cutterwould be broken, thereby constituting a slip feeding mechanism for theknee.

I claim- I 1. The combination with a cutter-carrying shaft, andback-gearing connected with and adapted to rotate said shaft, centerspindles carrying the blank to be cut, atelescopic shaft connected bygearing with one of said spindles, aswinging arm bearing gears forturning said telescopic shaft, the prime gear of which is engaged anddriven by the back-gearing which is connected with the cutter-carryinshaft, substantially as described.

2. The combination with a cutter-carrying shaft, back'gearingconnected'with and adapted to rotate the same, center spindles carryingthe blank to be out, a vertically moving knee supporting said centerspindles, a telescopic shaft connected by gearing with one of saidspindles, a swinging arm bearing gears for turning said telescopicshaft, the prime gear of whichis engaged and driven by the back-gearingwhich is connected with the cutter-carrying'shaft, substantially asdescribed.

3. The combination with a cutter-carrying shaft, back-gearing connectedwith and adapted to rotate the same, center spindles carrying the blankto be cut, a vertically moving knee, a horizontally moving carriageonsaid knee supporting said center spindles, a telescopic shaft connectedby gearing with one of said spindles, and moving toward and from theface of the machine, a swinging arm bearing gears for turning saidtelescopic shaft, the prime gear of which is engaged and driven by theback-gearing which is connected with the cuttercarryingshaft,subtantially as described.

4E. The combination with a cutter-carrying shaft, back-gearing connectedwith and adapted to rotate the same, center spindles carrying the blankto be cut, a vertically moving knee, a horizontally moving table sup-IIO ported'by said knee-supporting said center spindles, and movingacross the face of the machine, a telescopic shaft connected by gearingwith one of said spindles, a swinging arm bearing gears for turning saidtelescopic shaft, the prime gear of which is engaged and drive-n by theback-gearing which is connected with the cutter-carrying shaft, sub- Ifor said center spindles, and slip-feed mechanism for moving itvertically continuously, while the blank is being cut, in order that thecutting tool may gradually sink radially into the rotating blank,substantially as described. a '6. The combination with the hob-carryingshaft, means for rotating it, center spindles carrying the blank to becut, which turn on an axis at right angles to the axis of thehobcarrying shaft, gearing connected with and positively driven by themeans employed for rotating the hob-carrying shaft for driving one ofsaid spindles at a proportionate ratio to the hob-carrying shaft, avertically moving knee and slip feeding mechanism therefor, comprising afeeding screw, a power driven shaft for rotating said feeding screw, connected therewith by gearing, a cone pulley on said shaft, a main conepulley, and an intermediate cone pulley, and belts connecting said conepulleys, substantially as described.

7. The combination with a cutter-carrying shaft, means for rotating it,center spindles carrying the blank to be cut, turning on an axis atright angles to the axis of the cuttercarrying shaft, gearing fordriving one of said spindles, gear 0 on one of the shafts of saidgearing, gear 0 in mesh therewith, a telescopic shaft adapted to beconnected with said gearing or with the gear 0, and intermediate gearingconnecting said telescopic shaft with the means employed for rotatingthe cutter-carrying shaft, substantially as described.

8. The combination with the back-gearing of a milling machine, acutter-carrying shaft driven by it, center spindles carrying the work tobe done, turning on an axis at right angles to the axis of the entter-carryin g shaft, of an attachment interposed between saidback-gearing of the machine, and one of said center spindles, wherebythe latter is driven by the former at a proportionate ratio withrelation to the cutter-carrying shaft, and means for throwing saidgearing attachment into and out of action, substantially as described.

9. The combination of a cutter-carrrying shaft, means for rotating it,center spindles (1 ,01 carrying the work to be done, worm wheel atdetachably connected with the spindle d, worm d engagingit, and movablesupport therefor, telescopic shaft connected at one end with said worm(Z and at the other end with the mechanism employed for rotating thecutter-carrying shaft, substantially as described.

10. The combination with the usual back gearing of a milling machine,and spindles carrying the work to be done, of an attachment comprisingan arm supported upon the quill on the back gearing shaft, andadjustable on an axis coincident with the axis of said shaft, gearsborne by said arm, and a telescopic shaft, one end of which is connectedwith the hub of one of said gears, and the other end of which isconnected by gearing with one of the aforesaid spindles, operating torotate it, substantially as described.

11. The combination with the usual back gearing of a milling machine,and spindles carrying the Work to be done, of an attachment comprisingan arm supported upon a quill on the back gearing shaft, and adjustableon an axis coincident with the axis of said back gearing shaft, gearsadjustably connected with said arm, and a telescopic shaft, one end ofwhich is connected with the I hub of one of said gears, and the otherend of which is connected by gearing with one of the aforesaid spindles,operating to rotate it, substantially as described.

12. The combination of a cutter-carrying shaft, means for rotating it,center spindles d, d, carrying the work to be done, gearing connectingthe spindle (Z with the mechanism employed for rotating thecutter-carrying shaft, whereby said spindle and cutter-carrying shaftsare continuously revolved, parts of said gearing being movable into andout of cooperative relation with each other, aworm Wheel 01 on saidspindle d, worm d, and means for turning it manually, substantially asdescribed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

VOLNEY W. MASON, JR.

\Vitnesses:

B. J. NOYES, C. B. CRooKER.

